Moving walkways or escalators having anti-slip coating and method for applying an anti-slip coating

ABSTRACT

Escalator with a step band with several steps ( 4 ), or moving walk with a pallet band with pallets ( 4 ), wherein the steps ( 4 ) or pallets ( 4 ) are made of metal as brass, copper, NIROSTA, steel, magnesium, aluminum, and provided with an antislip coating. The antislip coating comprises a carbide hard substance that is embedded in a, or the, metallic matrix.

The invention relates to an escalator or a moving walk with a step bandwith steps, or respectively with a pallet band with pallets, for thetransportation of persons and/or objects, and steps or respectivelypallets that are provided with an antislip coating.

Transportation devices in the sense of the invention, which may also bereferred to as mobility devices, are escalators and moving walks with aplurality of tread units, escalator steps, or moving-walk palletsrespectively, that are joined to form an endless transporter. Users ofthe transportation devices stand on tread surfaces of the tread units orof the steps, or walk on the moving-walk pallets or escalator steps, inthe same direction as that in which the transportation devices travel ormove.

Usually, on account of their low weight, aluminum steps or metal steps,or aluminum pallets or metal pallets, are used. These steps or palletsare usually provided with ribs in the universally known manner. Despitethese ribs, the steps or pallets are slippery. If the transportationdevice is in the open air, or in an area that is near to an outsidedoor, the steps or pallets can become wet or dusty. In various cases, orin the fall, leaves or mud or airborne sand or soil or rubble or dustcan find their way onto the transportation device. Especially in thesesituations, the steps or pallets prove particularly slippery anddangerous.

Particular problems can arise depending on the footwear of the users.Thus, for example, shoes with leather soles, or rubber boots, areparticularly slippery.

For this reason, in some cases antislip coatings are used. From DE 10085 003 T1 and EP 1 169 256 B1 an antislip strip is known that is used onthe steps of an escalator.

Trials were performed with the application of fluoride resin. However,safety could not be lastingly assured with this measure. Furthermore,fluoride resin proved too costly and complicated to handle. Steps orpallets coated with fluoride resin have proved to be too expensive.There are, however, additional problems such as a lack of durability,since fluoride resin has a tendency to abrade rapidly and be easilyeroded. The reapplication of eroded fluoride resin necessitates the workof dismantling the entire escalator and removing the steps that must berepaired. Maintenance costs are thereby increased and, above all, duringsuch a maintenance operation the escalator or moving walk is notavailable for use.

Am important disadvantage of the coatings used hitherto is to be seen inthat the effect of the coating decreases relatively quickly. Inpractice, as said, this makes it necessary for the steps or pallets tobe removed and newly coated. The associated outlay or worktime is,however, too high. To increase the durability of the coating, asignificantly thicker layer would have to be applied. However, thickerlayers bring other problems of their own. So, for example, cleaning ofthe corresponding steps is made impossible.

It is here that the invention sets out to provide a remedy. Theinvention as it is characterized in Claim 1 solves the problem in that aspecial type of coating is selected which, relative to the previousmethods, is significantly thinner. That is to say, the invention goes ina direction that should not really promise success, since the expertwould be inclined to apply a thicker layer to increase the effectivenessand the ruggedness or durability.

A coating technique is used which ensures a very thin and highlyadhesive join between the coating and the aluminum step, or the aluminumpallet or the metal pallet. Furthermore, coating materials were selectedthat make possible a particularly intimate and reliable coating of themetal parts as aluminum parts or steel parts or NIROSTA parts or copperparts or brass parts or magnesium parts.

The advantages achieved by means of the invention are mainly to be seenin that the surface structure of the steps or pallets is not impaired bythe application of the coating. Furthermore, and in addition hereto, animportant advantage of the invention is that the function and safe,smooth, correct, jerkfree running of the entire transportation device isnot impaired by the coating. It is also important to emphasize that thecoating has a very long fatigue strength or abrasion resistance ordurability or wear resistance.

Preferred embodiments of the transportation device(s) according to theinvention are defined in the dependent claims.

The invention is described in detail below in relation to examples andby reference to the drawings. Shown are in

FIG. 1 a side view of an escalator according to the invention;

FIG. 2 a side view of a moving walk according to the invention;

FIG. 3 a plan view of a pallet, or step, of a transportation deviceaccording to the invention;

FIG. 4 an elevation of a pallet with antislip coating of atransportation device according to the invention;

FIG. 5 a plan view of an end-part, or head, of a transportation deviceaccording to the invention;

FIG. 6 a side view onto the comb plate, and onto the floor covers, of atransportation device according to the invention.

FIG. 1 shows an escalator 1 that connects a first level E1 with a secondlevel E2. The escalator 1 has a step band that consists of steps 4. Inthe case of a moving walk 1, as shown in FIG. 2, this has a pallet bandthat consists of pallets 4. A handrail 3 is arranged on a balustrade 2which at its lower end is held by a balustrade skirt.

FIG. 3 shows a diagrammatic representation of a pallet or step ontowhich between two and six strips of antislip coating 4.1 of carbide areapplied or sprayed.

FIG. 4 shows a pallet 4 with an antislip coating 4.1 of a hard metallayer wherein carbide hard substances (tungsten carbide, chromiumcarbide, titanium carbide, nickel carbide, or silicon carbide) areembedded in a metallic matrix. The carbide layer is applied to the steparea of the moving walk pallet 4 over the entire length. Preferably, twocarbide lengthwise strips are sprayed on.

FIG. 5 shows an end part E1, E2, or a head part, of a moving walk 1 orescalator 1 with antislip coating 4.1 which is applied to the pallets 4or steps 4. In addition, an antislip coating 4.1 is present on the combplates 7, 8, and on the floor covers 9. Moreover, and in addition, anantislip coating 4.1 is stripwise present on the combs. This embodimentallows the optimal protection against sliding away or slipping off. Thecarbide layer is sprayed or squirted in two to six strips per floorcover 9 or comb plate 7, 8.

FIG. 6 shows the diagrammatic illustration of the comb plates 7, 8, andof the floor covers 9 with antislip coating 4.1 of carbide. The hardmetal coating 4.1 of carbide hard material surrounds the metal parts oraluminum parts and deposits itself in the metallic matrix that ispresent. The surface of the components or metal parts is surrounded bythe antislip coating 4.1 in fine-grained and weather resistant manner.This is applied stripwise by means of a high-speed flame-sprayingprocess. By this means, an antislip surface forms that excellentlyprevents sliding or slipping.

In the description that now follows, instead of the terms “escalator” or“moving walk”, the term “transportation device” will be used.

Following below, various methods according to the invention of applyingan antislip coating 4.1 to the steps 4 of an escalator 1, or to thepallets 4 of a moving walk 1, are described.

According to the invention, a metallic powder material is acceleratedand heated by means of a spraying process. Then, by means of aspray-gun, a jet of the heated and accelerated powder material is aimedat the surface that is to be coated. This takes place in such mannerthat on impact with the metal surface, or alloy surface, or aluminumsurface that is to be coated, a homogeneous and fine-grained layer of acarbide hard material results, which is embedded in the metallic matrix.

The metallic powder material that is used is preferably a material thatcontains tungsten and/or chromium and/or titanium and/or nickel and/orsilicon.

Particularly preferred is a high-speed flame-spraying process in which amixture of oxygen and a flammable substance, preferably a flammable gas(propane or propylene), is used to heat and accelerate the powdermaterial. Instead of the flammable gas, a liquid flammable substance(e.g. kerosene) can be used as flammable substance. Preferably, usingnitrogen as carrier gas, the substance to be sprayed is led in powderform coaxially through a nozzle, surrounded by the flame, and therebyuniformly pre-melted and led out of the spray-gun.

In the case of the high-speed flame-spraying according to the invention,the powder material is sprayed with very high speed onto the metalworkpiece or alloy workpiece or aluminum workpiece that is to besprayed. The heat to completely melt the powder material is generated bythe reaction of oxygen and flammable substance (e.g. propane, propylene,natural gas, hydrogen, kerosene) in the combustion chamber. Thetemperatures that are attained in the flame reach up to approximately3000-4000° C., so that the powder material can be sprayed. The gasexpands and accelerates the powder material up to a speed of 400-900m/s. The workpiece surface, i.e. the metal surface or the alloy surfaceor the aluminum steps or aluminum pallets 4 need not be previouslysand-blasted or roughened since, on impact of the powder material on theworkpiece, a type of welding, or adhesive binding and bonding, takesplace between the powder material and the workpiece. In high-speedflame-spraying, through the high speed of the powder, a good adhesion ofthe metallic powder on the workpiece, and a low porosity, are attained.Furthermore, through the selection of a suitable metallic powder, abetter material can be created or established that is perfectly suitableas antislip material. The basic material (brass, copper, NIROSTA, steel,magnesium, aluminum) of the step 4 or pallet 4 is thereby enhanced andfaultlessly perfected. When tungsten, chromium, titanium, nickel, orsilicon is used as metallic powder, in high-speed flame-spraying,optimal layers of tungsten carbide, chromium carbide, titanium carbide,nickel carbide, or silicon carbide are produced. According to theinvention, the layer thickness is preferably between 0.08 mm and 0.2 mm.The porosity of the layers approaches zero.

The layers that occur with the method according to the invention aredenser, and adhere more firmly, than with other spraying methods such ascommercial flame-spraying, arc spraying, or plasma spraying.

The method according to the invention is particularly suitable for hardmetal layers wherein carbide hard substances (tungsten carbide, chromiumcarbide, titanium carbide, nickel carbide, or silicon carbide) areembedded in a metallic matrix. Layers can be manufactured that arecharacterized by a high wear resistance and/or permanence and/ordurability and/or resilience and/or constancy.

In high-speed flame-spraying, the emerging gas jet is used to pre-meltand melt the individual particles of the metallic powder material andaccelerate them to a high speed that is four to five times greater thanin conventional flame-spraying.

The high-speed flame-spraying process very effectively uses the highkinetic energy of the powder material and, to a limited extent, alsothermal energy, to create dense, compact layers with low porosity andhigh adhesive strength and/or high adhesive pull strength. Some of thelayers that are thus produced have an adhesive pull strength of morethan 83 Mpa (corresponding to approximately 83 N/mm2) and anexceptionally fine-grained surface.

The process uses, as said, a mixture of oxygen and a flammablesubstance, which is fed either as a mixture of oxygen and a flammablesubstance, or as a liquid flammable substance. There are thus two typesof spraying system: The gas-operated systems use propylene, propane,oxygen, or natural gas; in the liquid flammable substance systems,kerosene is used. Inside the spray-gun, the respective flammablesubstance is carefully mixed with oxygen, and emerges through a nozzle,where it is ignited. Preferably using nitrogen as carrier gas, thepowder material is led in powder form coaxially through this nozzle,surrounded by the flame, and thereby uniformly pre-melted. Through thegas mixture that emerges at exceptionally high speed, the powderparticles are accelerated and, with very high kinetic energy butmoderate temperature, are shot or sprayed or squirted onto the workpiecesurface. On impact, the powder particles are greatly flattened andsurround the base body. Through the low particle temperature bycomparison to the other thermal spraying methods, these layers have aforecastable chemical composition and are virtually homogeneous.Furthermore, the layers have a fine-grained structure.

Coatings of this type survive even harsh operating conditions andall-weather operation. Particularly the abrasion or wear is clearly lessthan with conventional antislip coatings. The antislip coating accordingto the invention thus offers not only an outstanding protection of thesteps 4 or pallets 4, but also a coating that even after relatively longuse hardly diminishes in its antislip effect, or not at all. Thethickness of the carbide layer remains constant for at least 5 to 10years, and there are absolutely no signs of wear or weathering ortendency to corrode.

Furthermore, and in addition, the new coating enables the standards EN115: Safety Rules for the Construction and Installation of Escalatorsand Passenger Conveyors, and AN American National Standard ASMEA17.1-2004: Safety Code for Elevators and Escalators, to be fulfilled.Further investigations show that DIN 51130 is also fulfilled with thehighest coefficient of friction R13.

The antislip coating additionally lengthens in outstanding manner thelifetime of the coated components.

Already after the coating, the antislip coating has a very fine-grainedsurface, a uniform composition, and a low porosity, and counts ascompletely processed. That is to say, it requires no further processingsteps and no further surface treatment.

It is an advantage of the invention that no pretreatment is required,and that the elaborate sand blasting or glass-bead blasting can beobviated in its entirety. This results in a great cost advantage and agreat manufacturing (process/cycle) advantage or worktime advantage.

According to the invention, the carbide layers are characterized by ahigh hardness of almost 1400 NV (Vickers hardness).

Particularly preferred is an embodiment of the invention that isrepresented in FIG. 3. According to this embodiment, instead of thecomplete surface being coated, only a number of strips 4.1 (preferablybetween two and six strips per pallet or step) are applied with stripwidths from 20 mm to 75 mm. Through this measure, the quantity of powdermaterial that is used is reduced. The antislip effect is nonethelessadequate, since the strips 4.1 offer adequate adhesion.

It is a further advantage of the invention that the manufacture of thecarbide layer on the pallet 4, or on the step 4, or on the comb plate 7,8, or on the floor cover 9, or on the machine room cover of atransportation device, in one work operation and fully automatically ispossible. Preferably, application of the carbide layer takes place bymeans of a robot, or by means of an automated plant apparatus, or bymeans of an automated coating apparatus.

Through use of the antislip coating according to the invention, thetheoretical angle of slope on the pallet 4, or on the step 4, or on thefloor cover 9, without slipping can be very significantly increasedrelative to known solutions. Consequently, the theoretical angle ofslope on the pallet 4, or on the step 4, can be increased from 11degrees to well over 40 degrees of slope, since the carbide layerexcellently prevents sliding or slipping. Furthermore, in the case ofwetness and/or soiling (dust, mud, airborne sand, soil, rubble, leaves),sliding or slipping can be optimally avoided and/or prevented by thecarbide layer.

As described, the invention can be equally applied to escalators andmoving walks.

1-10. (canceled)
 11. A method for applying an anti-slip coating of thetype wherein by means of a spraying process a powder material isaccelerated and heated, and by means of a spray-gun a jet of the heatedand accelerated powder material is directed at the surface that is to becoated, such that on impact with the surface that is to be coated ahomogeneous and fine-grained layer of a carbide hard material results,which is embedded in a metallic matrix, characterized in that: theprocess is chosen from the group consisting of high-speed flame-sprayingand plasma-spraying processes in which a mixture of oxygen and aflammable substance is used to heat and accelerate the powder material;and the powder material is applied to steps of an escalator or topallets of a moving walk.
 12. The method according to claim 11, whereinthe antislip coating is applied to the steps or pallets stripwise. 13.The method according to claim 11 or 12, wherein the powder material isled out of the spray-gun by means of or through a nozzle.
 14. The methodaccording to claim 11 or 12, characterized in that, by means of acarrier gas, the powder material is led coaxially through a nozzle,surrounded by the flame, and thereby uniformly pre-melted.
 15. Themethod according to claim 11 or 12, wherein the powder materialcomprises a material chosen from the group consisting of tungsten,chromium, titanium, nickel, and silicon.
 16. The method according toclaim 11 or 12, wherein the flammable substance is chosen from the groupconsisting of propane, propylene, natural gas, hydrogen, and kerosene.